通过 getStorageInfoSync() 获取的 currentSize 和我们通过其keys调用 getStorageSync() 方法计算出的值相差太多，前者为10393kb，后者为四十多kb。

相关代码如下示：

const sizeof = function(str, charset){
    str = typeof str === 'string' ? str : JSON.stringify(str);
    let total = 0;
    charset = charset ? charset.toLowerCase() : '';
    if(charset === 'utf-16' || charset === 'utf16'){
        for(let i = 0, len = str.length; i < len; i++){
            const charCode = str.charCodeAt(i);
            if(charCode <= 0xffff){
                total += 2;
            }else{
                total += 4;
            }
        }
    }else{
        for(let i = 0, len = str.length; i < len; i++){
            const charCode = str.charCodeAt(i);
            if(charCode <= 0x007f) {
                total += 1;
            }else if(charCode <= 0x07ff){
                total += 2;
            }else if(charCode <= 0xffff){
                total += 3;
            }else{
                total += 4;
            }
        }
    }
    return total;
}

const storageInfo = wx.getStorageInfoSync();
const {currentSize, limitSize, keys = []} = storageInfo;
keys.forEach((key, index) => {
    setTimeout(() => {
        const value = wx.getStorageSync(key);
        const size = sizeof(value);
    }, index * 20);
});